title: Midlife sleep characteristics associated with late life cognitive function.
abstract: OBJECTIVE
  Previous studies with limited follow-up times have suggested that sleep-related traits are associated with an increased risk of incident dementia or cognitive decline. We investigated the association between midlife sleep characteristics and late life cognitive function.
  
  
  METHODS
  A follow-up study with a median follow-up time of 22.5 (range 15.8-25.7) years assessing the association between midlife sleep characteristics and later cognitive function.
  
  
  METHODS
  Questionnaire data from 1981 were used in the assessment of sleep characteristics, use of hypnotics, and covariates at baseline. Between 1999 and 2007, participants were assigned a linear cognitive score with a maximum score of 51 based on a telephone interview (mean score 38.3, SD 6.1). Linear regression analyses were controlled for age, sex, education, ApoE genotype, and follow-up time.
  
  
  METHODS
  2,336 members of the Finnish Twin cohort who were at least 65 years of age.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Baseline short (< 7 h/day) and long (> 8 h/day) sleepers had lower cognitive scores than participants sleeping 7-8 h/ day (β = -0.84, P = 0.014 and β = -1.66, P < 0.001, respectively). As compared to good sleep quality, poor or rather poor sleep quality was associated with a lower cognitive score (β = -1.00, P = 0.011). Also, the use of hypnotics ≥ 60 days per year was associated with poorer cognitive function (β = -1.92, P = 0.002).
  
  
  CONCLUSIONS
  This is the first study indicating that midlife sleep length, sleep quality, and use of hypnotics are associated with late life cognitive function. Further confirmation is needed, but sleep-related characteristics may emerge as new risk factors for cognitive impairment.
authors.affiliation: Hjelt Institute, Department of Public Health, University of Helsinki, Finland ; Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: Jyri J
authors.initials: JJ
authors.lastname: Virta
authors.forename: Kauko
authors.initials: K
authors.lastname: Heikkilä
authors.forename: Markus
authors.initials: M
authors.lastname: Perola
authors.forename: Markku
authors.initials: M
authors.lastname: Koskenvuo
authors.forename: Ismo
authors.initials: I
authors.lastname: Räihä
authors.forename: Juha O
authors.initials: JO
authors.lastname: Rinne
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
mesh_terms: D000367:Age Factors; D000368:Aged; D001057:Apolipoproteins E / Q000235:genetics; D003071:Cognition / Q000502:physiology*; D060825:Cognitive Dysfunction / Q000209:etiology; D003704:Dementia / Q000209:etiology; D004200:Diseases in Twins / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012307:Risk Factors; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000150:complications; D011795:Surveys and Questionnaires; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
chemical_list: D001057:Apolipoproteins E; D006993:Hypnotics and Sedatives
keywords: Cognition; cohort studies; hypnotics and sedatives; risk factors; sleep